This invention relates to a modulation effect device of an electronic musical instrument.
In a prior art modulation effect device for imparting such a modulation effect as vibrato, chorus, ensemble (symphonic chorus) or the like, such analog delay elements as a bucket brigade device (BBD) and charge coupled device (CCD) have been used so as to produce a phase- or frequency-modulated signal from the delay elements by modulating the shift clock signal of the delay elements.
However, in a modulation effect device utilizing such analog delay elements, as the dynamic range with reference to an input signal to the analog delay element is narrow, S/N ratio is low thus resulting in a large noise.
To use a modulation effect device for an electronic musical instrument in which musical tone signals are converted into digital codes, the digital musical tone signals are first converted into analog signals by a D/A converter and then applied to the modulation effect device. It is necessary to use a filter having a sharp cut-off characteristic which makes it difficult to fabricate the filter in an integrated circuit, thus increasing the size.